4 PROFESSIONAL BOATBUILDERLETTERSPushing Batteries to the
Limit
To the Editor:
I read Nigel Calder’s article “Pushing
Batteries to the Limit” (Professional
BoatBuilder No. 170) with pleasure and
great interest. I converted my cruising
sailboat to a lithium-ion-battery-based
electrical system in May 2014 (see my
article “Chemical Conversion,” PBB No.
155). A er operating four seasons with
lithium-ion batteries since then, here is
an update, with additional information,
based on our real-world experience.
As Calder and I pointed out in our
articles, converting to lithium-ion bat-
teries is not a “drop-in.” My wife’s and
my four years of experience have con-
vinced me that this is likely the most
important point to remember when
contemplating such a conversion. All
aspects of the entire electrical systemLETTERS,
ETC.must be examined, including compo-
nents, control systems, cabling, com-
ponent and space cooling, and sizing of
components in the context of normal
boat operating patterns.
We have seen all the bene ts described
in these two PBB articles. In our case, our
primary goal was to reduce generator run
time. We exceeded our expectations. A er
nally getting the right alternator, dis-
cussed below, we are seeing approximately
80% reduction in genset run time com-
pared to AGM batteries. is is a good
way toward Nigel Calder’s goal: to replen-
ish the batteries with only the energy gen-
erated during normal boat operations.
I spent two years adapting and adjust-
ing various “small-case” alternators, but
never succeeded in solving the overheat-
ing issue caused by the alternator operating
at near 100% capacity for extended peri-
ods. I changed to a “large-case” alternator
two years ago, and it has worked awlessly. e large-case alternator does not t
alongside my engine as the original
small-case alternator did, so I developed
a robust custom “reverse mount” to moveReverse-mounted alternator with a 10-rib
serpentine belt and tensioning device.Letters172-ADFinal.indd 4 2/21/18 8:12 PM